Extrusion apparatus



July 14, 1959 R. A. WALTON 2,

EXTRUSION APPARATUS Filed March 9, 11956 N i: 1 Q nu m a INVEN TOR.Ric/10rd. Wa/zon g ro/ans);

United States Patent 2,894,623 EXTRUSION. APPARATUS Richard A. Walton,Edwardsville, Ill., assignor to The Dow Chemical Company, Midland,Mich., a corporation of Delaware Application March 9, 1956, Serial No.570,586 1 Claim. (Cl. 207-2) This invention relates to improvedextrusion press apparatus and is particularly related to apparatus usedin extruding wide, thin sections of light metal alloys.

Many wide, thin sections of light metal alloys are produced by anextrusion process. Because of the shape of the die used to produce thesections, dimensional problems due to uneven metal flow through the diehave limited the applications in which such sections could becommercially used.

It has been determined that metal flows more uniformly through dies ofthe above described type if a container and ram having a rectangulartransverse cross-sectional configuration is used. The use of rectangularcontainers results in greater adherence to dimensional tolerances thanis generally obtainable with round bore containers and also result inlowered extrusion pressure. Further, when rectangular containers areused differences in properties between the nose and butt of an extrusionare greatly reduced and there is no necessity for providing complicatedbafiles for restricting metal flow to various parts of the die.

On the other hand, the use of rectangular containers is subject to somedisadvantages. Rectangular containers require rectangular billets, andthe scalping requires milling or planing rather than the inexpensivelathe turning used in scalping cylindrical billets. When rectangularcontainers are used, it is required to maintain wider variety ofcontainers, rams and billets than are required in inventory whencylindrical containers are used in extrusion operations. Further, arectangular ram is less stable in operation than is a cylindrical ram.

A principal object of this invention is to provide improved extrusionapparatus which has the operative advantages of a rectangular containerwithout the inherent disadvantages attendant to the use of a rectangularcontainer.

Another object of this invention is to provide improved, more economicalapparatus for use in extruding wide, thin sections of light metals.

In accordance with this invention blocks are provided which are attachedto the entry side of an extrusion die which is adapted for use with acylindrical container. The blocks usually have a transverse crosssectional configuration which is a segment of a circle, the radius ofcurvature of each segment being that of the container. The blocks extendinto the container and are usually disposed diametrically opposite oneanother with the die opening being between the blocks. Such anarrangement results in the die end of the container being efiectivelyconverted into a rectangular type container With the attendantadvantages of such a container yet permitting a conventional roundbillet, container, and ram to be used in the extrusion operation.

The invention, as well as additional objects and advantages thereof,Will best be understood when the following detailed description is readin connection with the accompanying. drawing, in which:

Fig. 1 is a side elevational view, in section, of exis ,shown extrusionapparatus, indicated generally by the numeral 10, comprising a dieholder 12 having a die 14 integral therewith, backer 16, blocker 18, anda generally cylindrical container, indicated generally by the numeral20, which has a generally cylindrical bore 22 which is flared at the dieend 24 of the container to fit snugly against a taperedv side of the dieholder 12. A cylindrically shaped ram head 26, disposed within the bore,22, is used to extrude a billet 28 through the die 14 to produce a metalsection 32,

Sub-container blocks 34, 36 which have opposed parallel faces33, 35 and37, 39, respectively, are disposed within the container bore 22 and aresecured by any convenient means, as by pins 38, to and against the entryside 40 of the die 14. Each of the blocks 34, 36 has a transverse crosssectional configuration which is a segment of a circle, the radius ofcurvature of the curved part of the outer periphery 42 of the blocks 34,36 being substantially the same as the radius of curvature of the bore22.

Each of the blocks 34, 36 is provided with a sloping entrance face 44,46 which extends across that peripheral part of the blocks which is notshaped to conform to the curvature of the bore 22. Although the slopingentrance faces 44, 46 are very helpful in the operation of the blocks,they are not essential to the billet flow pattern into the die opening.The thickness or depth of the subcontainer blocks (except for thesloping entrance faces 44, 46) as a minimum should be of the distancefrom the'die opening to the block edge facing the die opening in orderto insure uniformity of flow through the die 14. In practice, too, aminimum thickness of the sub-container blocks should be about inch and amaximum thickness should usually not exceed 1 /2 inches because furtherincreases in thickness tend to be no more beneficial. The spacingbetween the blocks 34, 36 does not exceed sixty degrees as measuredradially from the center of the container bore 22 along the Wall of thecontainer bore 22 as may be seen in Fig. 2. The advantages of arectangular container are mostly the result of container shape adjacentto the die opening rather than the shape of the containers at distancesremote from the die opening.

In operation, a billet 28 is placed in the container bore 22 and isextruded through the die 14. The opening of the die 14 which isillustrated is used to produce flooring beams. The sub-container blocks34, 36 cause the billet 28 to be broken up into a mass which hasgenerally rectangular cross sectional configuration before the billetmaterial passes through the die 14. The blocks 34, 36 cause more evenmetal flow through the die 14, resulting in less bending and distortionof the extruded section 32,

The blocks 34, 36 are so simple and inexpensive to make that a specialset may be made for each die and permanently bolted thereto. Further,the use of subcontainer blocks substantially reduces and ofteneliminates the need for separate bafile plates which often must beplaced on the billet side of the die 14 to control the rate of flow ofbillet material to certain parts of the die.

In event billet material tends to slip between the curved outerperiphery 42 of the blocks 34, 36 and the wall of the bore 22, thesloping entrance faces 44, 46 are so disposed that the pressure exertedon the faces 44, 46 by the billet material during extrusion operationskeeps the blocks 34, 36 held against the wall of the bore 22.

The term billet material as used herein means light metals or theiralloys, extrudable plastic materials, or other metals adapted to becold-extruded through die openings. Magnesium alloys are common alloyswhich may be extruded in apparatus in which subcontainer blocks'34, 36are incorporated.

That which is claimed is:

In extrusion apparatus which includes an extrusion press having anextrusion die including a die opening, said die communicating with andhaving a flat surface facing into a cylindrically shaped container borehaving a generally cylindrical ram moveably disposed therein, theimprovement comprising a pair of blocks disposed within said bore, eachof said blocks having two parallel opposed surfaces, one of saidparallel opposed surfaces of each block abutting against said flat diesurface, each block having a peripheral surface which is disposedagainst said cylindrical bore in close fitting relationship therewith,each of said blocks having a plurality of means for maintaining saidblocks in predetermined position within the bore and against said diesurface, the blocks being disposed opposite to one another and onopposite sides of the die opening, the spacing between the blocks beingless than sixty degrees of are as measured radially from the center ofthe 'bore along the bore Wall between the blocks, whereby the generalshape of the container adjacent to the die is changed from a cylindricalto a substantially rectangular cavity which conforms generally to theoutline configuration of the die opening.

References Cited in the file of this patent UNITED STATES PATENTS413,460 Roney Oct. 22, 1889 567,606 McCool et al Sept. 15, 18961,395,217 Begot Oct. 25, 1921 1,836,821 Singer Dec. 15, 1931 1,840,472Singer Jan. 12, 1932 2,389,876 Sequin Nov. 27, 1945 2,408,627 Green Oct.1, 1946 FOREIGN PATENTS 376,132 France May 3, 1907 588,835 France Feb..11, 1925 1,116,005 France Jan. 23, 1 956

